This is an expression for a female (or male), to describe the physical appearance. Specifically, when someone looks damn good from about 100 yards, but upon closer viewing, is really nasty and/or unattractive.

The expression is pronounced:
Gee, Eff, Eff, Bee, Eff, Eff, Gee

“I thought she was hot, from across the park, then I got closer and realized she was gffbffg, so just walked right by her and threw up in the bushes.”